tag datastructure?

Okay, I crawled the LJ code for two days before seeing this today:

Also this month we've fixed up a bunch of bugs with tags, and we're now exposing far more tag information to S2 styles -- S2 style authors now have access to information like how many times a tag was used, who can see the tag, and more. Keep an eye out for styles adding this information.

Which is pretty much what I was trying to find: a way to display how many times the tag has been used and in what context in order to customize the list of tags used by a journal.